Sucker rod apparatus and method

ABSTRACT

The present disclosure relates to a fiberglass rod with connectors on each end. Each connector has a rod-receiving receptacle having an open end, a closed end, and axially spaced annular wedge shaped surfaces such that the compressive forces between the rod and the respective connector are defined by the shape of the wedged surfaces.

FIELD

The present disclosure relates generally to oil well sucker rods. Inparticular, the disclosure relates to oil well sucker rods made offiberglass with connectors on each end and the manufacture thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate preferred embodiments of thedisclosure and together with the general description of the disclosureand the detailed description of the preferred embodiments given below,serve to explain the principles of the disclosure.

FIG. 1 illustrates a typical pumping system for use with the technologyof the present disclosure.

FIG. 2 is a cross-sectional view of an embodiment of a sucker rod and anassociated end fitting within the scope of the present disclosure.

FIG. 2A is an exploded view of the angle A between the leading edge andthe trailing edge of a wedged-shaped portion of the wedge system.

FIG. 3 is a sectional view of the sucker rod and end fitting combinationillustrated in FIG. 2 taken along the section line 3-3.

FIG. 4 is a sectional view of the sucker rod and end fitting combinationillustrated in FIG. 2 taken along the section line 4-4.

FIG. 5 is a sectional view of the sucker rod and end fitting combinationillustrated in FIG. 2 taken along the section line 5-5.

FIG. 6 is a sectional view of the sucker rod and end fitting combinationillustrated in FIG. 2 taken along the section line 6-6.

FIG. 7 is a sectional view of the sucker rod and end fitting combinationillustrated in FIG. 2 taken along the section line 1-7.

FIG. 8 is a sectional view of the sucker rod and end fitting combinationillustrated in FIG. 2 taken along the section line 8-8.

FIG. 9 is a graph of the relationship between the length of the leadingedge and trailing edge of each wedged-shaped portion in the wedge systemof the present disclosure.

FIG. 10 is a cross-sectional view of another embodiment of a sucker rodand an associated end fitting within the scope of the present disclosure

The depicted embodiments of the sucker rod and associated connectors aredescribed below with reference to the listed Figures.

The above general description and the following detailed description aremerely illustrative of the generic disclosure, and additional modes,advantages, and particulars of this disclosure will be readily suggestedto those skilled in the art without departing from the spirit and scopeof the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In many oil wells, the pressure in the oil reservoir is not sufficientto lift the oil to the surface. In such cases, it is conventional to usea sub-surface pump to force the oil from the well. A pumping unitlocated at the surface drives the sub-surface pump. The pumping unit isconnected to the sub-surface pump by a string of sucker rods. Thepumping unit moves the sucker rod string up and down to drive thesub-surface pump.

Originally, a sucker rod was a special steel pumping rod. A sucker rodis, typically, a steel rod that is used to make up the mechanicalassembly between the surface and the downhole components of a rodpumping system. Several sucker rods were screwed together to make up themechanical link, or sucker rod string, from a beam-pumping unit on thesurface to the subsurface pump at the bottom of a well. The sucker rodswere threaded on each end and manufactured to dimension standards andmetal specifications set by the petroleum industry. Typically, suckerrods have been in the lengths of 25 or 30 feet (7.6 or 9.1 meters), andthe diameter varies from ½ to 1⅛ inches (12 to 30 millimeters).

Thus, sucker rod pumping is a method of artificial lift in which asubsurface pump located at or near the bottom of the well and connectedto a string of sucker rods is used to lift the well fluid to thesurface. The weight of the rod string and fluid is counterbalanced byweights attached to a reciprocating beam or to the crank member of abeam-pumping unit or by air pressure in a cylinder attached to the beam.

Due to the heavy weight of the steel sucker rods, large pumping unitswere required and pumping depths were limited. It is now preferable touse sucker rods made of fiberglass with steel connectors. The fiberglasssucker rods provide sufficient strength, and weigh substantially lessthan steel rods.

Since the development of the fiberglass sucker rod, there have beencontinued efforts to improve the sucker rod, and particularly, therelationship between the steel connectors and the successive rods.

FIG. 1 illustrates a generic pumping system 20. The pumping system 20includes a pump drive 22, which is a conventional beam pump, or pumpjack and is connected to a downhole pump 26 through a sucker rod string24 inserted into wellbore 28. The sucker rod string 24 can comprise acontinuous sucker rod 10, which extends from the downhole pump 26 to thepumping system 20, a series of connected sucker rods 10, a series ofconventional length rods connected together, or any combination thereof.The pump drive 22 includes a horsehead 22A, a beam 22B, a gearbox 22 cand a motor 22D. Preferably, the sucker rod 10 is a fiberglass orcomposite rod. As described herein, the sucker rod string 24 may be thesame as the continuous sucker rod 10 when the continuous sucker rod 10is a one-piece rod that extends substantially between the pump drive 22and the sub-surface pump 26.

FIG. 2 is a cross-sectional view of an embodiment of the sucker rod 10comprising a fiber composite rod 200 and associated end fitting 100within the scope of the present disclosure. The sucker rod 10 comprisesone or more end fittings 100 and the fiber composite rod 200. The fibercomposite rod 200 has a first end 202 and a second end (notillustrated).

Typically, there are end fittings 100 on each end of the fiber compositerod 200 for coupling together a plurality of fiber composite rods 200.The end fitting 100 comprises an exterior surface 102, a closed end 104,an open end 106, and an interior surface 108. The interior surface 108comprises a wedge system 110. The present disclosure provides that thewedge system 110 can have any number of wedges with three wedgespreferred. The wedge system 110 defines a cavity 112 in the end fitting100.

Further, the wedge system 110 comprises a plurality of wedged-shapedportions 114.

Each wedged-shaped portion 114 has an apex 116, a leading edge 118 and atrailing edge 120 extending from the apex 116. Each apex 116 forms aperimeter 122 within the cavity 112 that is the narrowest part of thecavity 112 associated with each wedge shaped portion 114. The leadingedge 118 is longer than the trailing edge 120 with the leading edge 118facing the open end 106 and the trailing edge 120 facing the closed end104 with respect to each wedge shaped portion 114.

The first wedge shaped portion 114A is proximate to the closed end 104for receiving compressive forces that are greater than the compressiveforces associated with the other wedged-shaped portion 114B, C.Particularly, the first wedged-shaped portion 114A receives greatercompressive forces than the compressive forces for which a second wedgeshaped portion 114B receives that is proximate to the firstwedged-shaped portion 114. A third wedge shaped portion 114C between thesecond wedge shaped portions 114B and the open end 106 receivescompressive forces that are less than the compressive forces associatedwith the first and second wedge shaped portions 114A, 114C. Therefore,the compressive forces create a force differential along each wedgeshaped portion 114 greater at the closed end 104 of the end fitting 100and decreasing toward the open end 106 of the end fitting 100.

As the compressive forces associated with the first wedged-shapedportion 114A deteriorate the structural integrity of the firstwedged-shaped portion 114A, then, it has been found that theuncompensated for compressive forces of the first wedged-shaped portion114A are transferred to and accepted by the second wedged-shaped portion114B. Similarly, as the compressive forces associated with the secondwedged-shaped portion 114B deteriorate the structural integrity of thesecond wedged-shaped portion 114B, then it has been found that theuncompensated for compressive forces of the second wedged-shaped portion114B are transferred to and accepted by the third wedged-shaped portion114C.

Thus, a force transfer continuum is created by the wedge system 110. Theforce transfer continuum provides for a constant effectiveness betweenthe end fitting 100 and the fiber composite rod 200 as the wedge system110 deteriorates from one wedged-shaped portion 114 to the nextwedged-shaped portion 114 of the wedge system 110.

The sucker rod 10 has a plurality of longitudinal cross-sections of thewedged-shaped portions 114, which forms a plurality of frustro-conicalshapes within the cavity 112.

The wedge shaped portions 114 of the sucker rod 10 create differentcompressive forces on each respective edge 118, 120 thereof with thecompressive force being approximately proportional to a length of eachedge 118, 120. In one embodiment, the compressive force on each edge118, 120 is directly proportional to the length of each edge 118, 120.Further, the plurality of wedge shaped portions 114 are determined bythe angle associated between the leading edge 118 and the trailing edge120.

An adhesive or epoxy 130 is used to sufficiently bond with the fibercomposite rod 200 and engage with the end fitting 100. It is appreciatedthat any adhesive substance that will sufficiently bond with the fibercomposite rod 200 and engage with the end fitting 100 may be used. Theadhesive or epoxy 130 is placed in the cavity 112 and cured to bond withthe fiber composite rod 200 in the cavity 112 for fixedly securing theend fitting 100 with the fiber composite rod 200.

In one embodiment, the angle A between the leading edge 118 and thetrailing edge 120 of each wedge shaped portion is obtuse. FIG. 2illustrates an angle A associated with each wedged-shaped portion 114 ofthe wedge system 110.

FIG. 2A is an exploded view of the angle A of the second wedged-shapedportion 114B of the wedge system 110. The fiber composite rod 200 isillustrated in the end fitting 100. The end fitting 100 defines theleading edge 118B and the trailing edge 120B to form the cavity 112. Theangle between the leading edge 118B and the trailing edge 120B definesthe angle A. Generally, the leading edge 118, the trailing edge 120 andthe fiber composite rod 200 form a scalene triangle with the longestside of the scalene triangle being along the fiber composite rod 200,the shortest side of the scalene triangle being along the trailing edge120, and the intermediate side of the scalene triangle being along theleading edge 118.

FIG. 3 is a sectional view of the fiber composite rod 200 and endfitting 100 combination illustrated in FIG. 2 taken along the sectionline 3-3. The end fitting 100 is exterior of the fiber composite rod 200with the cavity 112 there between. The cavity 112 between the fibercomposite rod 200 and the end fitting 100 forms a gap G3.

FIG. 4 is a sectional view of the fiber composite rod 200 and endfitting 100 combination illustrated in FIG. 2 taken along the sectionline 4-4. The end fitting 100 is exterior of the fiber composite rod 200with the cavity 112 there between. The cavity 112 between the fibercomposite rod 200 and the end fitting 100 forms a gap G4. The gaps G3and G4 are associated with the first wedged-shaped portion 114A of thewedge system 110.

FIG. 5 is a sectional view of the fiber composite rod 200 and endfitting 100 combination illustrated in FIG. 2 taken along the sectionline 5-5. The end fitting 100 is exterior of the fiber composite rod 200with the cavity 112 there between. The cavity 112 between the fibercomposite rod 200 and the end fitting 100 forms a gap G5.

FIG. 6 is a sectional view of the fiber composite rod 200 and endfitting 100 combination illustrated in FIG. 2 taken along the sectionline 6-6. The end fitting 100 is exterior of the fiber composite rod 200with the cavity 112 there between. The cavity 112 between the fibercomposite rod 200 and the end fitting 100 forms a gap G6. The gaps G5and G6 are associated with the second wedged-shaped portion 114B of thewedge system 110.

FIG. 7 is a sectional view of the fiber composite rod 200 and endfitting 100 combination illustrated in FIG. 2 taken along the sectionline 7-7. The end fitting 100 is exterior of the fiber composite rod 200with the cavity 112 there between. The cavity 112 between the fibercomposite rod 200 and the end fitting 100 forms a gap G7.

FIG. 8 is a sectional view of the fiber composite rod 200 and endfitting 100 combination illustrated in FIG. 2 taken along the sectionline 8-8. The end fitting 100 is exterior of the fiber composite rod 200with the cavity 112 there between. The cavity 112 between the fibercomposite rod 200 and the end fitting 100 forms a gap G8. The gaps G7and G8 are associated with the second wedged-shaped portion 114C of thewedge system 110.

The smaller gaps G3, G5, G7 associated with each wedged-shaped portion114 are substantially constant having essentially the same dimension.Similarly, the larger gaps G4, G6, G8 associated with each wedged-shapedportion 114 are substantially constant having essentially the samedimension. The symmetry provided by the relationship of the minimum gapsG3, G5, G7 and the maximum gaps G4, G6, G8 provides unforeseen results.Particularly, the symmetry provided by the relationship of the minimumgaps G3, G5, G7 and the maximum gaps G4, G6, G8 greatly enhances thestability and ability of the fiber composite rod 200 and end fitting 100combination to accept enhanced compressive and back pressure forcesassociated with the reciprocating environment in which the sucker rods10 are used.

FIG. 9 is a graph of the relationship between the length of the leadingedge 118 and trailing edge 120 of each wedged-shaped portion 114 in thewedge system 110 of the present disclosure. As illustrated in FIG. 2,the leading edge 118 is progressively longer from the closed end 104 ofthe end fitting 100 to the open end 106 of the end fitting 100.Similarly, the trailing edge 120 is progressively longer from the closedend 104 of the end fitting 100 to the open end 106 of the end fitting100. The functions defined by these relationships are illustrated inFIG. 9. Particularly, a line having a slope or gradient defines thefunction associated with the trailing edge 120, and a line having aslope or gradient defines the function associated with the leading edge118.

The relationship of the function associated with the trailing edge 120and the function associated with the leading edge 118 provides insightto the unforeseen effectiveness of the wedge system 110 of the presentdisclosure. It has been found that the rate of increase of the length ofthe leading edge 118 with respect to the rate of increase of the lengthof the trailing edge 120, as defined by the slope or gradient of eachassociated function, provides an enhanced sucker rod 10 and sucker rodsystem. The slope of the leading edge 118 associated with the wedgesystem 110 of the present disclosure is greater than the slope of thetrailing edge 120 associated with the wedge system 110 of the presentdisclosure.

The wedge system 110 of the present disclosure as applied to a suckerrod 10 provides unforeseen effectiveness not before appreciated. Thecombination of the wedged-shaped portions 114, the relationship of theleading edge 118 to the trailing edge 120, the symmetry of the minimumgaps G3, G5, G7 and the maximum gaps G4, G6, G8 result in a wedge system110 that provides improved and unpredicted functionality. Particularly,the improved and unpredicted functionality of the sucker rod 10 havingthe wedge system 110 of the present disclosure greatly enhances thestability of the sucker rod 10 and ability of the fiber composite rod200 and end fitting 100 combination to accept enhanced compressive andback pressure forces associated with the reciprocating environment inwhich the sucker rods 10 are used.

FIG. 10 is a cross-sectional view of another embodiment of a sucker rod50 and associated end fitting 100 within the scope of the presentdisclosure. The sucker rod 50 comprises one or more end fittings 100 anda fiber composite rod 200. The fiber composite rod 200 has a first end202 and a second end (not illustrated).

Typically, there are end fittings 100 on each end of the fiber compositerod 200 for coupling together a plurality of fiber composite rods 200.The end fitting 100 comprises an exterior surface 102, a closed end 104,an open end 106, and an interior surface 108. The interior surface 108comprises a wedge system 110. The present disclosure provides that thewedge system 110 can have any number of wedges as indicated by thebroken line between the first wedged-shaped portion 114A and the secondwedged-shaped portion 114B. The wedge system 110 defines a cavity 112 inthe end fitting 100.

The wedge system 110 comprises a plurality of wedged-shaped portions114. Each wedged-shaped portion 114 has an apex 116, a leading edge 118and a trailing edge 120 extending from the apex 116. Each apex 116 formsa perimeter 122 within the cavity 112 that is the narrowest part of thecavity 112 associated with each wedge shaped portion 114. The leadingedge 118 is longer than the trailing edge 120 with the leading edge 118facing the open end 106 and the trailing edge 120 facing the closed end104 with respect to each wedge shaped portion 114.

The first wedge shaped portion 114A is proximate to the closed end 104for receiving compressive forces that are greater than the compressiveforces associated with the other wedged-shaped portions 114B, C, etc.Particularly, the first wedged-shaped portion 114A receives greatercompressive forces than the compressive forces for which a second wedgeshaped portion 114B receives that is proximate to the firstwedged-shaped portion 114A. A third wedge shaped portion 114C betweenthe second wedge shaped portions 114B and the open end 106 receivescompressive forces that are less than the compressive forces associatedwith the first and second wedge shaped portions 114A, 114C. Therefore,the compressive forces create a force differential along each wedgeshaped portion 114 greater at the closed end 104 of the end fitting 100and decreasing toward the open end 106 of the end fitting 100.

As the compressive forces associated with the first wedged-shapedportion 114A deteriorate the structural integrity of the firstwedged-shaped portion 114A, then it has been found that theuncompensated for compressive forces of the first wedged-shaped portion114A are transferred to and accepted by the second wedged-shaped portion114B. Similarly, as the compressive forces associated with the secondwedged-shaped portion 114B deteriorate the structural integrity of thesecond wedged-shaped portion 114B, then it has been found that theuncompensated for compressive forces of the second wedged-shaped portion114B are transferred to and accepted by the third wedged-shaped portion114C.

Thus, a force transfer continuum is created by the wedge system 110regardless of the number of wedged-shaped portions 114 comprise thewedge system 110. The force transfer continuum provides for a constanteffectiveness between the end fitting 100 and the fiber composite rod200 as the wedge system 110 deteriorates from one wedged-shaped portion114 to the next wedged-shaped portion 114 of the wedge system 110.

The wedge shaped portions 114 of the sucker rod 50 create differentcompressive forces on each respective edge 118, 120 thereof with thecompressive force being approximately proportional to a length of eachedge 118, 120. In one embodiment, the compressive force on each edge118, 120 is directly proportional to the length of each edge 118, 120.Further, the plurality of wedge shaped portions 114 are determined bythe angle associated between the leading edge 118 and the trailing edge120.

An adhesive or epoxy 130 is used to sufficiently bond with the fibercomposite rod 200 and for engagement with the end fitting 100. It isappreciated that any adhesive substance that will sufficiently bond withthe fiber composite rod 200 and engage with the end fitting 100 may beused. The adhesive or epoxy 130 is placed in the cavity 112 and cured tobond with the fiber composite rod 200 in the cavity 112 for fixedlysecuring the end fitting 100 with the fiber composite rod 200.

In one embodiment, the angle A between the leading edge 118 and thetrailing edge 120 of each wedge shaped portion is obtuse. FIG. 2Aillustrates an angle A associated with each wedged-shaped portion 114 ofthe wedge system 110 with respect to the present disclosure.

The longitudinal cross sections of the concaved portions 110 formfrustro-conical shapes. The concaved portions 110 create differentcompressive forces on each respective surface thereof with thecompressive force being approximately proportional to the length of eachsurface. The compressive force on each surface increases toward theclosed end 104 and decreases toward the open end 106. The compressiveforce on each first surface 118 is proportional to the length of eachsurface. The compressive force on each second surface 120 isproportional to the length of each second surface.

The plurality of concaved portions 110 are determined by the angleassociated between the first surface 118 and the second surface 120 ofeach concaved surface 110. The angle between the first surface 118 andthe second surface 120 of each concaved surface 110 is obtuse. Further,each wedge shape portion 114 may have a length proportional to thecompressive force applied to the wedge shape 114. The wedge shape 114has a length that increases from the closed end 104 to the open end 106of the end fitting 100. The wedge shaped portions 114 may have a lengththat decreases from the closed end 104 to the open end 106 of the endfitting 100.

In yet another embodiment, a method for manufacturing a sucker rod isprovided. The method comprises the steps of constructing an end fittingcomprising an exterior surface, a closed end, an open end, and aninterior surface. The interior surface comprises at least three wedgeshaped portions defining a cavity. The wedge shaped portions have anapex and a first and second length extending from the apex. The apexforms a perimeter that is the narrowest part of the cavity associatedwith each wedge shaped portion such that the first length is longer thanthe second length with the first length facing the open end and thesecond length facing the closed end with respect to each wedge shapedportion. The method further comprises engaging an end of a fibercomposite rod into the cavity of the end fitting for creating a voidbetween the fiber composite rod and the wedge shaped portions of the endfitting. Thereafter, injecting an epoxy into the void to bond with thefiber composite rod and to fixedly engage the wedge shaped portions ofthe end fitting for securing the end fitting to the fiber composite rod.This arrangement causes the stress to increase the elastic limit withoutpermanent alteration of the fiber composite rod and epoxy combination inthe cavity of the end fitting.

Thus, a first wedge shaped portion proximate to the closed end receivescompressive forces that are greater than the compressive forces forwhich a second wedge shaped portion proximate to the open end receives,and an intermediate wedge shaped portion between the first and secondwedge shaped portions for receiving compressive forces that areintermediate of the first and second wedge shaped portions. Such thatthe compressive forces create a force differential along the wedgeshaped portion greater at the closed end of the fitting and decreasingtoward the open end of the fitting.

The method for manufacturing a sucker rod may further comprise the stepof creating different compressive forces on each respective surface ofthe wedge shaped portions with the compressive force being approximatelyproportional to the length of each surface.

Further, the method for manufacturing a sucker rod may comprise the stepof the compressive force on each surface increasing toward the closedend and decreasing toward the open end.

Still further, the method for manufacturing a sucker rod may comprisethe compressive force on each first surface being proportional to thelength of each surface.

Yet still further, the method for manufacturing a sucker rod maycomprise the compressive force on each second surface being proportionalto the length of each second surface.

The method for manufacturing a sucker rod may comprise the plurality ofwedge shaped portions being determined by the angle associated betweenthe first surface and the second surface of each concaved surface. Themethod for manufacturing a sucker rod may have the angle between thefirst surface and the second surface of each concaved surface beingobtuse.

The method for manufacturing a sucker rod wherein each wedge shape has alength proportional to the compressive force applied to the wedge shape.The method for manufacturing a sucker rod wherein each wedge shape has alength that increases from the closed end to the open end of the endfitting. The method for manufacturing a sucker rod wherein each wedgeshape has a length that decreases from the closed end to the open end ofthe end fitting.

FIG. 3 is a graph that illustrates the relationship of the stress versesthe strain with respect to the effect on the elastic limit within thescope of the present disclosure. The yield strength or yield point of amaterial is defined in engineering and materials science as the stressat which a material begins to deform plastically. Prior to the yieldpoint the material will deform elastically and will return to itsoriginal shape when the applied stress is removed. Once the yield pointis passed some fraction of the deformation will be permanent andnon-reversible.

Knowledge of the yield point is vital when designing a component sinceit generally represents an upper limit to the load that can be applied.It is also important for the control of many materials productiontechniques such as forging, rolling, or pressing. In structuralengineering, this is a soft failure mode which does not normally causecatastrophic failure or ultimate failure unless it accelerates buckling.It is often difficult to precisely define yielding due to the widevariety of stress-curves exhibited by real materials. In addition, thereare several possible ways to define yielding.

True elastic limit 1 is the lowest stress at which dislocations move.This definition is rarely used, since dislocations move at very lowstresses, and detecting such movement is very difficult. Proportionalitylimit 2 is an amount of stress that is proportional to strain (i.e.,Hooke's law), so the stress-strain graph is a straight line, and thegradient will be equal to the elastic modulus of the material.

Elastic limit (yield strength) 3 is the elastic limit, where permanentdeformation will occur. The lowest stress at which permanent deformationcan be measured. This requires a manual load-unload procedure, and theaccuracy is critically dependent on equipment and operator skill. Forelastomers, such as rubber, the elastic limit is much larger than theproportionality limit. Also, precise strain measurements have shown thatplastic strain begins at low stresses. Yield point is the point in thestress-strain curve at which the curve levels off and plasticdeformation begins to occur.

FIG. 4 is a graph that illustrates the relationship of the stress versesthe strain with respect to the enhanced strain achieved with the presentdisclosure. The structure of the present disclosure achieves the abilityto receive and adapt to enhanced stress. The ability to receive andaccommodate the enhanced amounts of stress provides for enhanced straincharacteristics.

The invention has been shown in only one of its embodiments. It shouldbe apparent to those skilled in the art that the invention is not solimited, but is susceptible to various changes and modifications withoutdeparting from the spirit of the invention.

It is understood that the steps of the method described above or asclaimed is not required to be performed in the order as disclosed. It isfurther understood that not all of the steps are necessary to carry outthe claimed method and different embodiments of the method may not useall of the steps as disclosed above.

While the present disclosure has been described with emphasis on certainembodiments, it should be understood that within the scope of theappended claims, the present locating sub system and method could bepracticed other than as specifically described herein. Thus, additionaladvantages and modification will readily occur to those skilled in theart. The disclosure in its broader aspects is therefore not limited tothe specific details, representative apparatus, and the illustrativeexamples shown and described herein. Accordingly, the departures may bemade from the details without departing from the spirit or scope of thedisclosed general inventive concept.

1. An end fitting for a sucker rod comprising: an exterior surface, aclosed end, an open end, and an interior surface, the interior surfacecomprising a wedge system defining a cavity wherein the wedge systemcomprises three wedge shaped portions having an apex, a leading edge anda trailing edge, each apex forming a perimeter of equal dimension withinthe cavity that is the narrowest part of the cavity associated with eachwedge shaped portion such that the leading edge is longer than thetrailing edge with the leading edge facing the open end and the trailingedge facing the closed end with respect to each wedge shaped portion,the leading edge is shorter at the closed end a increases progressivelyfrom the closed end to the open end thereby compensating for thecompression of the sucker rod in the end fitting, the trailing edge isshorter at the closed end a increases progressively from the closed endto the open end thereby compensating for the back pressure associatedwith the sucker rod in the end fitting, the first wedge shaped portionproximate to the closed end for receiving compressive forces that aregreater than the compressive forces for which the second wedge shapedportion receives, and the second wedge shaped portion receivingcompressive forces that are greater than the compressive forces forwhich the third wedge shaped portion receives, such that the compressiveforces create a force differential along the wedge system greater at theclosed end of the fitting and decreasing toward the open end of thefitting.
 2. The end fitting of claim 1 wherein the wedge system createsdifferent compressive forces on each respective wedge shaped portionthereof with the compressive force being approximately proportional to alength of each edge.
 3. The end fitting of claim 2 wherein thecompressive force on each edge is directly proportional to the length ofeach edge.
 4. The end fitting of claim 1 wherein the wedge shapedportions are determined by an angle associated the apex between theleading edge and the trailing edge.
 5. The end fitting of claim 4wherein the angle between the leading edge and the trailing edge of eachconcaved surface is obtuse.
 6. The end fitting of claim 1 furthercomprising a fiber composite rod having an end engaged centrally withinthe end fitting.
 7. The end fitting of claim 6 further comprising asecond end fitting engaged with a second end of the fiber composite rod.8. The end fitting of claim 6 further comprising an epoxy placed in thecavity for bonding with the fiber composite rod in the cavity forfixedly securing the end fitting with the fiber composite rod.
 9. Theend fitting of claim 8 wherein the epoxy is uniform in thickness betweenthe wedge shaped portions and the fiber composite rod such that themaximum thickness is substantially constant and the minimum thickness issubstantially constant.
 10. The end fitting of claim 6 furthercomprising a beveled recess in the closed end for accepting andcentrally aligning the fiber composite rod within the end fitting.
 11. Asucker rod comprising: a fiber composite rod having a first end and asecond end, and end fittings on each end of the fiber composite rod forcoupling together a plurality of fiber composite rods, the end fittingcomprising: an exterior surface, a closed end, an open end, and aninterior surface, the interior surface comprising a wedge systemdefining a cavity wherein the wedge system comprises three wedge shapedportions having an apex, a leading edge and a trailing edge, each apexforming a perimeter of equal dimension within the cavity that is thenarrowest part of the cavity associated with each wedge shaped portionsuch that the leading edge is longer than the trailing edge with theleading edge facing the open end and the trailing edge facing the closedend with respect to each wedge shaped portion, the leading edge isshorter at the closed end a increases progressively from the closed endto the open end thereby compensating for the compression of the suckerrod in the end fitting, the trailing edge is shorter at the closed end aincreases progressively from the closed end to the open end therebycompensating for the back pressure associated with the sucker rod in theend fitting, the first wedge shaped portion proximate to the closed endfor receiving compressive forces that are greater than the compressiveforces for which the second wedge shaped portion receives, and thesecond wedge shaped portion receiving compressive forces that aregreater than the compressive forces for which the third wedge shapedportion receives, such that the compressive forces create a forcedifferential along the wedge system greater at the closed end of thefitting and decreasing toward the open end of the fitting.
 12. Thesucker rod of claim 11 wherein the wedge system creates differentcompressive forces on each respective wedge shaped portion thereof withthe compressive force being approximately proportional to a length ofeach edge.
 13. The sucker rod of claim 12 wherein the compressive forceon each edge is directly proportional to the length of each edge. 14.The sucker rod of claim 11 wherein the wedge shaped portions aredetermined by an angle associated the apex between the leading edge andthe trailing edge.
 15. The sucker rod of claim 14 wherein the anglebetween the leading edge and the trailing edge of each concaved surfaceis obtuse.
 16. The sucker rod of claim 11 wherein the fiber compositerod having each end engaged centrally within the end fitting.
 17. Thesucker rod of claim 16 further comprising an epoxy placed in the cavityfor bonding with the fiber composite rod in the cavity for fixedlysecuring the end fitting with the fiber composite rod.
 18. The suckerrod of claim 17 wherein the epoxy is uniform in thickness between thewedge shaped portions and the fiber composite rod such that the maximumthickness is substantially constant and the minimum thickness issubstantially constant.
 19. The sucker rod of claim 16 furthercomprising a beveled recess in the closed end for accepting andcentrally aligning the fiber composite rod within the end fitting.
 20. Asucker rod comprising: a fiber composite rod having a first end and asecond end, and end fittings on each end of the fiber composite rod forcoupling together a plurality of fiber composite rods, the end fittingcomprising: an exterior surface, a closed end, an open end, and aninterior surface, the interior surface comprising a wedge systemdefining a cavity wherein the wedge system comprises an interior, atleast one intermediate and an exterior wedge shaped portion, each wedgeshaped portion having an apex, a leading edge and a trailing edge, eachapex forming a perimeter of equal dimension within the cavity that isthe narrowest part of the cavity associated with each wedge shapedportion such that the leading edge is longer than the trailing edge withthe leading edge facing the open end and the trailing edge facing theclosed end with respect to each wedge shaped portion, each leading edgeis shorter at the closed end a increases progressively from the closedend to the open end thereby compensating for the compression of thesucker rod in the end fitting, each trailing edge is shorter at theclosed end a increases progressively from the closed end to the open endthereby compensating for the back pressure associated with the suckerrod in the end fitting, the interior wedge shaped portion proximate tothe closed end for receiving compressive forces that are greater thanthe compressive forces for which the intermediate wedge shaped portionreceives, and the intermediate wedge shaped portion receivingcompressive forces that are greater than the compressive forces forwhich the exterior wedge shaped portion receives, such that thecompressive forces create a force differential along the wedge systemgreater at the closed end of the fitting and decreasing toward the openend of the fitting.
 21. The sucker rod of claim 20 wherein the wedgesystem creates different compressive forces on each respective wedgeshaped portion thereof with the compressive force being approximatelyproportional to a length of each edge.
 22. The sucker rod of claim 21wherein the compressive force on each edge is directly proportional tothe length of each edge.
 23. The sucker rod of claim 20 wherein thewedge shaped portions are determined by an angle associated the apexbetween the leading edge and the trailing edge.
 24. The sucker rod ofclaim 23 wherein the angle between the leading edge and the trailingedge of each concaved surface is obtuse.
 25. The sucker rod of claim 20wherein the fiber composite rod has each end engaged centrally withinthe end fitting.
 26. The sucker rod of claim 25 further comprising anepoxy placed in the cavity for bonding with the fiber composite rod inthe cavity for fixedly securing the end fitting with the fiber compositerod.
 27. The sucker rod of claim 26 wherein the epoxy is uniform inthickness between the wedge shaped portions and the fiber composite rodsuch that the maximum thickness is substantially constant and theminimum thickness is substantially constant.
 28. The sucker rod of claim25 further comprising a beveled recess in the closed end for acceptingand centrally aligning the fiber composite rod within the end fitting.29. A sucker rod comprising: a fiber composite rod having a first endand a second end, and end fittings on each end of the fiber compositerod for coupling together a plurality of fiber composite rods, the endfitting comprising an exterior surface, a closed end, an open end, andan interior surface, the interior surface comprising a wedge systemdefining a cavity wherein the wedge system comprises an interior, atleast one intermediate and an exterior wedge shaped portion, each wedgeshaped portion having an apex, a leading edge and a trailing edge, eachapex forming a perimeter of equal dimension within the cavity that isthe narrowest part of the cavity associated with each wedge shapedportion such that the leading edge is longer than the trailing edge withthe leading edge facing the open end and the trailing edge facing theclosed end with respect to each wedge shaped portion, each leading edgeis shorter at the closed end a increases progressively from the closedend to the open end thereby compensating for the compression of thesucker rod in the end fitting, each trailing edge is shorter at theclosed end a increases progressively from the closed end to the open endthereby compensating for the back pressure associated with the suckerrod in the end fitting, the ratio of the trailing edge to the leadingedge of the interior wedge shaped portion is larger than the ratio ofthe trailing edge to the leading edge of each subsequent adjacenttrailing edge to leading edge ratio, the interior wedge shaped portionproximate to the closed end for receiving compressive forces that aregreater than the compressive forces for which the intermediate wedgeshaped portion receives, and the intermediate wedge shaped portionreceiving compressive forces that are greater than the compressiveforces for which the exterior wedge shaped portion receives, such thatthe compressive forces create a force differential along the wedgesystem greater at the closed end of the fitting and decreasing towardthe open end of the fitting.
 30. The sucker rod of claim 29 wherein thewedge system creates different compressive forces on each respectivewedge shaped portion thereof with the compressive force beingapproximately proportional to a length of each edge.
 31. The sucker rodof claim 30 wherein the compressive force on each edge is directlyproportional to the length of each edge.
 32. The sucker rod of claim 29wherein the wedge shaped portions are determined by an angle associatedthe apex between the leading edge and the trailing edge.
 33. The suckerrod of claim 32 wherein the angle between the leading edge and thetrailing edge of each concaved surface is obtuse.
 34. The sucker rod ofclaim 29 wherein the fiber composite rod has each end engaged centrallywithin the end fitting.
 35. The sucker rod of claim 34 furthercomprising an epoxy placed in the cavity for bonding with the fibercomposite rod in the cavity for fixedly securing the end fitting withthe fiber composite rod.
 36. The sucker rod of claim 35 wherein theepoxy is uniform in thickness between the wedge shaped portions and thefiber composite rod such that the maximum thickness is substantiallyconstant and the minimum thickness is substantially constant.
 37. Thesucker rod of claim 34 further comprising a beveled recess in the closedend for accepting and centrally aligning the fiber composite rod withinthe end fitting.
 38. A method for manufacturing a sucker rod comprisingthe steps of: constructing an end fitting comprising an exteriorsurface, a closed end, an open end, and an interior surface, theinterior surface comprising a wedge system defining a cavity wherein thewedge system comprises an interior, at least one intermediate and anexterior wedge shaped portion, each wedge shaped portion having an apex,a leading edge and a trailing edge, each apex forming a perimeter ofequal dimension within the cavity that is the narrowest part of thecavity associated with each wedge shaped portion such that the leadingedge is longer than the trailing edge with the leading edge facing theopen end and the trailing edge facing the closed end with respect toeach wedge shaped portion, engaging an end of a fiber composite rod intothe cavity of the end fitting for creating a symmetrical void betweenthe fiber composite rod and the wedge shaped portions of the end fittingwhereby the symmetrical void has symmetry along the longitudinal axis ofthe fiber composite rod, injecting an epoxy into the void to bond withthe fiber composite rod and to fixedly engage the wedge shaped portionsof the wedge system of the end fitting for securing the end fitting tothe fiber composite rod such that as the epoxy is uniform in thicknessbetween the wedge shaped portions and the fiber composite rod wherebythe maximum thickness is substantially constant and the minimumthickness is substantially constant, the interior wedge shaped portionproximate to the closed end for receiving compressive forces that aregreater than the compressive forces for which the intermediate wedgeshaped portion receives, and the intermediate wedge shaped portionreceiving compressive forces that are greater than the compressiveforces for which the exterior wedge shaped portion receives, such thatthe compressive forces create a force differential along the wedgesystem greater at the closed end of the fitting and decreasing towardthe open end of the fitting.
 39. The method for manufacturing a suckerrod of claim 38 further comprising the step of creating differentcompressive forces on each respective surface of the wedge shapedportions with the compressive force being approximately proportional tothe length of each edge.
 40. The method for manufacturing a sucker rodof claim 39 further comprising the step of the compressive force on eachsurface increasing toward the closed end and decreasing toward the openend.
 41. The method for manufacturing a sucker rod of claim 40 whereinthe compressive force on each first edge is proportional to the lengthof each edge.
 42. The method for manufacturing a sucker rod of claim 41wherein the compressive force on each second edge is proportional to thelength of each second edge.
 43. The method for manufacturing a suckerrod of claim 38 wherein the plurality of wedge shaped portions aredetermined by the angle associated between the first surface and thesecond surface of each concaved surface.
 44. The method formanufacturing a sucker rod of claim 43 wherein the angle between thefirst surface and the second surface of each concaved surface is obtuse.45. The method for manufacturing a sucker rod of claim 38 wherein eachwedge shape has a length proportional to the compressive force appliedto the wedge shape.
 46. The method for manufacturing a sucker rod ofclaim 38 wherein each wedge shape has a length that increases from theclosed end to the open end of the end fitting.
 47. The method formanufacturing a sucker rod of claim 38 wherein each wedge shape has alength that decreases from the closed end to the open end of the endfitting.